Corrosion resistant alloys



Patented Feb. 20, 1549 UNITED STATES PATENT OFFICE CORROSION RESISTANTALLOYS William Marriott Kay, Manchester, England, as-

signor to Driver-Harris Company, Harrison, 7 N. J., a corporation of NewJersey No Drawing. Application April 29, 1939, Serial No. 270,844. InGreat Britain May 2, 1938 3 Claims. (01. 75-171) This invention relatesto corrosion resistant; minute. The evaporation loss was continuouslynickel-chromium alloys. replaced by boiled water and the liquid was con-For certain purposes alloys are required which tinuously stirred. In twoseries of tests the liqhave high heat resistance and also corrosionreuid contained 2 /2% by weight of sulphuric acid sistance, as forexample, in the manufacture of and the liquid temperatures were roomtempera- 5 conveyor chains, which have to carry goods ture and 60 C. Intwo other series of tests, the

through a furnace for annealing or other heat liquid contained 5% byweight of sulphuric acid treatment and then through a spray which mayand the liquid temperatures were room temperaconsist of a dilutesolution of one or more acids. ture and 60 C.

0 Although the corrosion resistance of the straight It should beremarked that it is a matter of nickel-chromium alloys is quite good, itmay, in general knowledge that the difference in corrosion examples suchas that above referred to, be the resistance of nickel chromium alloysis not atcorrosion resistance which determines the life of tributable torelatively small difierences in chro the alloy rather than the heatresistance, and mium content. It can be attributed therefore in 5 thepresent invention is concerned with improvthe following test figurestodifierences in silicon ing such corrosion resistance. content.

The invention comprises the addition to nickelchromium alloys of from 3%to 6% of silicon. Test results The best results appear to be achievedwhen the D addition of silicon is approximately 4%. E??? z Thenickel-chromium alloy may contain from brea 11g ff tt fif 10% to 30% ofchromium. The remainder of the iiigas 831163 Pmmds alloy may be nickelsave for the silicon. The nickel content may be partly replaced by iron,Low menu 3 648 319 cobalt, tungsten, vanadium, molybdenum, zirmaterial{High 7,250 698 3 conium, manganese and uranium. The alloy may alsocontain traces of alkaline earth metals, or TESTS I 36% H1504 FOR 500HOURS the rare earth metals, and may also contain the 630 3 0 usualsmall quantities of impurities of such ele- Roomt m we Lowsil con.-5,895 1 ments as carbon, sulphur, phosphorus and aluo w a pa E :,fjjjj11% 28 2 minium High sillcom.-. 6,940 691 351 30 Experimental tests haveshown that a siliconaddition within the range 3-6% reduces the at- TESTSIN 1 4 FOR 500 HOURS tack of acid upon nickel-chromium alloys to a I 90m6 235 considerable extent. 'Roomtem Low silicon- 5,8 For this purposefour series of tests were made, 0 O W iggg sil i gifI 51 3 22 5 eachupon six pieces of metal of two difierent H1811 6,760 634 282compositions as follows:

The above results show the marked superiority Chromium gg Chromium 3 ofthe higl?1 silicondfilloy particularly under the 40 Silicon; 4 Silicon 1wi gfi g i gf Balance Nlckel Balance 1. ,A heat resistant, corrosionresistant alloy 1 being taken as n p e of the Preferred capable of beingworked into strip or wire form alloy and N 2 as n pl of a known allfiyin consisting essentially of 10 to 30 percent chrouse y for suchpurposes. mium, 3 to 6 percent silicon, balance nickel.

The e a i 2. A heat resistant, corrosion resistant alloy mg g i i g imig gg had the follow capable of being worked into strip or wire formconsisting essentially of substantially 20 percent (1) Heavy Stnp x inchx t chromium 3 to 6 percent silicon,'balance nickel.

(2) Light strip 3 1nchesx0.25 inch x .020 inch 3. A a resistant,corrosion resistant alloy (3) Round wire 8 inches x .057 inch diametercapable of being Worked into strip or wire f r Each sample was fastenedby a wire of the same consisting essentially of substantially'20 percentcomposition as the sample, to the periphery of chromium, substantially 4percent silicon, bala fibre disc partly immersed in the test liquid ancenickel.

I and revolved once every tour minutes. A given WILLIAM MARRIO'II Kpoint on any specimen was immersed tor one

